阅读说明：本技术 稳定获取指定粒度高纯硅溶胶的方法 (Method for stably obtaining high-purity silica sol with specified granularity ) 是由 马惠琪 于 2020-08-03 设计创作，主要内容包括：一种稳定获取指定粒度高纯硅溶胶的方法,是在硅酸钠粉末中加入蒸馏水制成硅酸钠溶液,再移置高压釜中,通入碱性气体并在气体隔离剂的保护下制得碱性硅酸钠水合物/缔合物,然后通过电泳分离得到去金属离子硅酸钠溶液,再通过分子筛分选器分选获得指定粒径范围段的硅溶胶液,然后对指定粒径范围段硅溶胶液进行闪蒸浓缩和脱气,获得指定粒径范围段硅溶胶浓缩液,再在气体隔离剂的保护下,强力搅拌、静止冷却、陈化和二次脱气,得到指定粒度高纯硅溶胶。本发明可稳定获取2～40nm粒径范围内无团聚的指定粒度高纯硅溶胶,且硅溶胶粒度可在2～40nm之间任意选择获取,其二氧化硅纯度＞99.99wt％,满足多种精密加工、生产和研发的需求。(A method for stably obtaining high-purity silica sol with specified granularity includes adding distilled water into sodium silicate powder to prepare sodium silicate solution, moving the sodium silicate solution into a high-pressure kettle, introducing alkaline gas, preparing alkaline sodium silicate hydrate/associated complex under protection of gas isolating agent, obtaining metal ion-removed sodium silicate solution through electrophoretic separation, obtaining silica sol solution with specified particle size range section through separation of a molecular sieve separator, performing flash evaporation concentration and degassing on the silica sol solution with specified particle size range section to obtain silica sol concentrated solution with specified particle size range section, and performing strong stirring, static cooling, aging and secondary degassing under protection of the gas isolating agent to obtain high-purity silica sol with specified granularity. The method can stably obtain the high-purity silica sol with the specified granularity and no agglomeration within the grain diameter range of 2-40 nm, the granularity of the silica sol can be randomly selected and obtained within the range of 2-40 nm, the purity of the silica is more than 99.99 wt%, and the requirements of various precision processing, production and research and development are met.)

1. A method for stably obtaining high-purity silica sol with specified granularity is characterized by comprising the following steps:

s10) adding distilled water into sodium silicate powder, stirring and heating to dissolve the sodium silicate powder, and preparing a sodium silicate solution with the weight percentage concentration of 3-5 wt% of sodium silicate;

s20) transferring the sodium silicate solution into an autoclave, introducing alkaline gas and a gas isolating agent under the condition of normal temperature stirring, maintaining the high pressure inside the autoclave, and dissolving a certain amount of the alkaline gas and the gas isolating agent into the sodium silicate solution to stabilize the pH value of the sodium silicate solution between 11 and 13 to prepare an alkaline sodium silicate hydrate/association complex;

s30) carrying out electrophoretic separation on the alkaline sodium silicate hydrate/associated complex through an electrophoretic separator to remove Fe3⁺、Mn²⁺、Na⁺、K⁺Ionizing to obtain a metal ion-removed sodium silicate solution;

s40) feeding the sodium silicate solution with metal ions removed into a molecular sieve separator, and sieving the sodium silicate solution under the pressure lubrication of a gas lubricant to obtain a silica sol solution with a specified particle size range;

s50) placing the silica sol liquid with the designated particle size range section in a vacuum flash evaporator for flash evaporation concentration of the silica sol liquid with the designated particle size range section, and then removing the alkaline gas and the gas isolating agent dissolved in the silica sol liquid with the designated particle size range section to obtain the silica sol concentrated liquid with the designated particle size range section, wherein the weight percentage of the silicon dioxide is 12-60 wt%, and the gas content is less than 10 PPM;

s60) introducing a gas isolating agent into the silica sol concentrated solution in the specified particle size range, strongly stirring, standing, cooling, aging, and degassing for the second time to obtain the high-purity silica sol with the specified particle size.

2. The method for stably obtaining a high purity silica sol of a specified particle size according to claim 1, wherein:

the high-purity silica sol with the specified particle size is silica sol with different particle size sections within the particle size range of 2-40 nm, the viscosity of the high-purity silica sol with the specified particle size at 25 ℃ is 5-40 mPa.s, the weight percentage concentration of the silica is 12-60 wt%, and the weight percentage purity of the silica colloid is 99.99-99.99999 wt%.

3. The method for stably obtaining a high purity silica sol of a specified particle size according to claim 1, wherein: the sodium silicate powder has a purity of more than 99.5 wt%.

4. The method for stably obtaining a high purity silica sol of a specified particle size according to claim 1, wherein:

the alkaline gas is any one of ammonia gas or ammonia-linked gas or a mixture of the two gases in any proportion;

the gas isolating agent is any one gas or a mixture of a plurality of gases in any proportion of carbon monoxide, nitrogen, methane, ethane or propane.

5. The method for stably obtaining a high purity silica sol of a specified particle size according to claim 1, wherein: in step S10), the heating is performed such that the temperature of the mixture of the sodium silicate powder and the distilled water is raised to 105-120 ℃.

6. The method for stably obtaining high purity silica sol with specified particle size according to claim 1, wherein in step S10), the method further comprises promoting the dissolution of the sodium silicate powder by means of an external electric field and high speed stirring and maintaining high pressure in the kettle, specifically:

putting sodium silicate powder into a reaction kettle with a high-speed stirring device, adding distilled water, inserting two electrodes into a mixture of the sodium silicate powder and the distilled water, applying direct current with the voltage of 10-50V and the current of 1-5A to the electrodes to form an electric field, starting the high-speed stirring device to enable the stirring speed to reach 500-1000 rpm, and keeping the internal pressure of the reaction kettle to be 0.12-0.20 MPa to dissolve the sodium silicate powder.

7. The method for stably obtaining a high purity silica sol of a specified particle size according to claim 1, wherein in step S20):

stirring at the normal temperature is carried out at a stirring speed of 800-1200 rpm;

the high pressure in the high-pressure kettle is kept to be 0.3-0.5 MPa;

the introduced alkaline gas has a volume percentage concentration of 5-30 vol%, and the introduced gas isolating agent has a volume percentage concentration of 70-95 vol%.

8. The method for stably obtaining a high purity silica sol of a specified particle size according to claim 1, wherein:

and step S30) is to keep the alkali sodium silicate hydrate/association complex to perform electrophoretic separation operation under the conditions that the pressure is 0.3-0.5 MPa and the temperature is 20-25 ℃, wherein the electrophoretic separator is a positive dielectric or negative dielectric electrophoretic hydrocyclone separator.

9. The method for stably obtaining a high purity silica sol of a specified particle size according to claim 1, wherein:

the molecular sieve of the molecular sieve separator is any one or a mixture of more of a silicon dioxide molecular sieve, a silicon nitride molecular sieve and a silicon carbide ceramic molecular sieve, and the effective aperture of the molecular sieve is 2-40 nm;

the molecular sieve separator is formed by dividing any one or more of the silicon dioxide molecular sieve, the silicon nitride molecular sieve and the silicon carbide ceramic molecular sieve and a mixture of a plurality of the silicon dioxide molecular sieve, the silicon nitride molecular sieve and the silicon carbide ceramic molecular sieve into 6-8 sections of aperture layers according to different effective apertures, and filling the aperture layers in a tubular container in a layered mode, wherein each section of aperture layer corresponds to one section of silica sol particle size range;

the gas lubricant is composed of any one or a mixture of two of nitrogen and argon, and the pressure of the gas lubricant is 2-6 MPa.

10. The method for stably obtaining a high purity silica sol of a specified particle size according to claim 1, wherein:

the vacuum flash evaporator is also provided with an ultrasonic device and a powerful stirring device, and the flash evaporation concentration is realized by emitting frequency of 120-400 KH from the ultrasonic device_ZThe ultrasonic wave is subjected to ultrasonic oscillation and strong stirring at a stirring speed of 800-2000 rpm, and the removal operation is performed at a temperature of 45-85 ℃ at the silica sol liquid in the specified particle size range.

Technical Field

The invention relates to a method for obtaining silica sol, in particular to a method for stably obtaining high-purity silica sol with specified granularity, belonging to the technical field of production and preparation of inorganic nano silica sol.

Background

The silica sol is odorless and nontoxic, and the molecular formula can be expressed as mSiO₂·nH₂O, belonging to colloidal solution.

Since the silica sol particles are fine, have a relatively large specific surface area, are colorless and transparent, do not affect the natural color of the covered object, have low viscosity, and are permeable to water, the silica sol particles are excellent in dispersibility and permeability when mixed with other substances, and when the silica sol evaporates, the colloidal particles can be firmly attached to the surface of the object, and silica bonding is formed between the particles, and the silica sol is a good adhesive.

The silica sol has the characteristics of good caking property, high temperature resistance, film forming property, gel property, charge property, large specific surface area, no toxicity, no odor and the like, is widely applied to precision casting, refractory materials, coatings, textile industry, paper industry, battery industry, catalyst industry, and can also be used as a water purifying agent, a clarifying agent, a dispersing agent of a picture tube coating, a polishing agent of a semiconductor element, and the like, and is used for treating carbon products, chemical fabric ornaments, reinforced foam rubber and the like.

With the rapid development of the electronic industry, the fine chemical industry, the advanced material industry and other industries, the industries have higher and more rigorous requirements on the quality of the silica sol, and particularly, the industries put forward higher requirements on the particle size distribution range of silica sol particles, the purity of the silica sol, the particle size of the silica sol particles and the like, so that products meeting the requirements can be supplied to the market in a large scale and meet the requirements of related scientific research and production.

At present, numerous patent literature documents on the preparation of silica sols can be retrieved, among which:

CN200310121304.5, CN200510075740.2, CN200510024230.2, CN200780050856.8, CN201680045088.6 and the like, respectively, disclose methods for producing silica sol using an alkali catalyst, organoalkoxysilane or a condensate thereof, acid phosphate, an organic solvent, a water-soluble Ca salt, an aqueous solution of Mg salt and the like as a raw material or a reactant;

patent documents CN201610987058.9, CN96100907.1 and the like disclose methods for preparing silica sol by ion exchange method, and further by processes such as ultrasonic chemical method in acidic environment and microporous ultrafiltration membrane sieving in acidic environment;

patent documents such as cn200780027760.x, CN201110253283.7, CN201110002320.7, CN86104144, CN201480032863.5, CN201410505702.5, CN96100907.1, CN102432027A, CN1644497A, CN201610987058.9, CN201610206120.6, CN201810278823.9, CN1301905C, US2577484 and CN96122871.7 also disclose related technologies relating to the preparation of silica sol.

In addition, the monograph works of "research on preparing silica sol by elemental silica dissolution method" in the text of Tianhua, Chenlianxi and Liu (Liaoning chemical industry, 2007, 36 (8): 509-510, 514), the Sundao "research on preparing nano-silica from silica sol" (university of Qingdao science, 2008, 29 (4): 291-293, 301), the preparation and theoretical research of modified silica sol (university of southwestern (natural science), 2013, 35 (1): 113-118), the research works of preparing catalyst grade silica sol of Zhenghua, Wenpeng, Chengxiang, Lanqian and xuting (silicate report, 2016, 35 (2): 416-420), and the like, also disclose the research results of the silica sol preparation process.

However, the patent documents and the monographs of the papers do not provide specific methods and clear suggestions on how to stably obtain high-purity silica sol with specified particle size, thereby influencing the needs of scientific research and production in the industries of electronics, fine chemistry, advanced materials and the like.

Disclosure of Invention

In order to solve the defects of the prior art, the embodiment of the invention provides a method for stably obtaining high-purity silica sol with specified granularity, aiming at:

by the method provided by the embodiment of the invention, the existing facility equipment and related technologies in the prior art are utilized, and the high-purity silica sol with the specified granularity is rapidly and stably obtained through creative combined application and control of special process conditions, so that the social requirements are met, and the corresponding economic benefits are obtained.

In order to achieve the above purpose, the embodiments of the present invention provide the following technical solutions:

a method for stably obtaining high-purity silica sol with specified granularity is characterized by comprising the following steps:

s10) adding distilled water into sodium silicate powder, stirring and heating to dissolve the sodium silicate powder, and preparing a sodium silicate solution with the weight percentage concentration of 3-5 wt% of sodium silicate;

s20) transferring the sodium silicate solution into an autoclave, introducing alkaline gas and a gas isolating agent under the condition of normal temperature stirring, maintaining the high pressure inside the autoclave, and dissolving a certain amount of the alkaline gas and the gas isolating agent into the sodium silicate solution to stabilize the pH value of the sodium silicate solution between 11 and 13 to prepare an alkaline sodium silicate hydrate/association complex;

s30) carrying out electrophoretic separation on the alkaline sodium silicate hydrate/associated complex through an electrophoretic separator to remove Fe³⁺、Mn²⁺、Na⁺、K⁺Ionizing to obtain a metal ion-removed sodium silicate solution;

s40) feeding the sodium silicate solution with metal ions removed into a molecular sieve separator, and sieving the sodium silicate solution under the pressure lubrication of a gas lubricant to obtain a silica sol solution with a specified particle size range;

s50) placing the silica sol liquid with the designated particle size range section in a vacuum flash evaporator for flash evaporation concentration of the silica sol liquid with the designated particle size range section, and then removing the alkaline gas and the gas isolating agent dissolved in the silica sol liquid with the designated particle size range section to obtain the silica sol concentrated liquid with the designated particle size range section, wherein the weight percentage of the silicon dioxide is 12-60 wt%, and the gas content is less than 10 PPM;

s60) introducing a gas isolating agent into the silica sol concentrated solution in the specified particle size range, strongly stirring, standing, cooling, aging, and degassing for the second time to obtain the high-purity silica sol with the specified particle size.

Further, the high-purity silica sol with the specified particle size is silica sol with different particle size sections, the particle size range of the silica sol is 2-40 nm, the viscosity of the high-purity silica sol with the specified particle size at 25 ℃ is 5-40 mPa.s, the weight percentage concentration of the silica is 12-60 wt%, and the weight percentage purity of the silica colloid is 99.99-99.99999 wt%.

Further, the sodium silicate powder has a purity of > 99.5 wt% in weight percent.

Further, the alkaline gas is any one of ammonia gas or a mixture of two gases in any proportion, and the gas isolating agent is any one of carbon monoxide, nitrogen gas, methane, ethane or propane or a mixture of a plurality of gases in any proportion.

Further, in step S10), the heating is performed such that the temperature of the mixture of the sodium silicate powder and the distilled water is increased to 105 to 120 ℃.

Further, in step S10), the method further includes promoting the dissolution of the sodium silicate powder by applying an electric field and stirring at a high speed and maintaining a high pressure in the kettle, specifically:

putting sodium silicate powder into a reaction kettle with a high-speed stirring device, adding distilled water, inserting two electrodes into a mixture of the sodium silicate powder and the distilled water, applying direct current with the voltage of 10-50V and the current of 1-5A to the electrodes to form an electric field, starting the high-speed stirring device to enable the stirring speed to reach 500-1000 rpm, and keeping the internal pressure of the reaction kettle to be 0.12-0.20 MPa to dissolve the sodium silicate powder.

Further, in step S20):

stirring at the normal temperature is carried out at a stirring speed of 800-1200 rpm;

the high pressure in the high-pressure kettle is kept to be 0.3-0.5 MPa;

the introduced alkaline gas has a volume percentage concentration of 5-30 vol%, and the introduced gas isolating agent has a volume percentage concentration of 70-95 vol%.

Further, the step S30) is to keep the alkali sodium silicate hydrate/association complex under the conditions of 0.3-0.5 MPa pressure and 20-25 ℃ for electrophoretic separation, wherein the electrophoretic separator is a positive or negative dielectrophoresis hydrocyclone.

Further:

the molecular sieve of the molecular sieve separator is any one or a mixture of more of a silicon dioxide molecular sieve, a silicon nitride molecular sieve and a silicon carbide ceramic molecular sieve, and the effective aperture of the molecular sieve is 2-40 nm;

the molecular sieve separator is formed by dividing any one or more of the silicon dioxide molecular sieve, the silicon nitride molecular sieve and the silicon carbide ceramic molecular sieve and a mixture of a plurality of the silicon dioxide molecular sieve, the silicon nitride molecular sieve and the silicon carbide ceramic molecular sieve into 6-8 sections of aperture layers according to different effective apertures, and filling the aperture layers in a tubular container in a layered mode, wherein each section of aperture layer corresponds to one section of silica sol particle size range;

the gas lubricant is composed of any one or a mixture of two of nitrogen and argon, and the pressure of the gas lubricant is 2-6 MPa.

Further:

the vacuum flash evaporator is also provided with an ultrasonic device and a powerful stirring device, and the flash evaporation concentration is realized by emitting frequency of 120-400 KH from the ultrasonic device_ZThe ultrasonic wave is carried out under the conditions of ultrasonic oscillation and strong stirring with the stirring speed of 800-2000 r/min;

the removal operation is carried out at the temperature of 45-85 ℃ of the silica sol liquid in the section with the specified particle size range.

Compared with the prior art, the embodiment of the invention has the beneficial effects and obvious progress that:

1) the embodiment of the invention provides a method for stably obtaining high-purity silica sol with specified granularity, which comprises the steps of adding distilled water into sodium silicate powder, dissolving to prepare a sodium silicate solution, then moving the sodium silicate solution into a high-pressure kettle, introducing alkaline gas, under the protection of a gas isolating agent, obtaining alkaline sodium silicate hydrate/associated complex, then carrying out electrophoretic separation on the alkaline sodium silicate hydrate/associated complex to obtain a metal ion-removed sodium silicate solution, then sending the metal ion-removed sodium silicate solution into a molecular sieve separator to obtain silica sol liquid with a specified particle size range section, then carrying out flash evaporation concentration and degassing on the silica sol liquid with the specified particle size range section to obtain silica sol concentrated liquid with the specified particle size range section, stirring by a powerful machine under the isolation protection of the gas isolating agent, then standing, standing and degassing, Cooling, aging, and degassing for the second time to obtain high-purity silica sol with specified granularity;

2) the method for stably obtaining the high-purity silica sol with the specified granularity can stably obtain the high-purity silica sol with the specified granularity, which has no agglomeration in the grain diameter range of 2-40 nm, can be randomly adjusted in the grain diameter range of 2-40 nm, has the viscosity of 5-40 mPa.s and the concentration of 12-60 wt% at 25 ℃, has the silica purity of more than 99.99 wt%, even 99.99999 wt%, can meet the requirements of precision electronic device processing and other high-tech products production research and development, and has wide market prospect and predictable considerable economic benefit;

3) the method for stably obtaining the high-purity silica sol with the specified granularity, provided by the embodiment of the invention, has the advantages of unique and stable process, strong operability, no pollution to the environment in the production process, energy conservation and environmental protection, provides positive social benefits, and can obtain better economic benefits for enterprises, thereby having great popularization and application values.

Drawings

To more clearly illustrate the technical solution of the present invention, the drawings required for the embodiment of the present invention will be briefly described below.

Obviously:

the drawings in the following description are only part of the embodiments of the present invention, and it is obvious to those skilled in the art that other drawings can be obtained according to the drawings without creative efforts, but the other drawings also belong to the drawings required to be used by the embodiments of the present invention.

Fig. 1 is a schematic block diagram of a process flow of stably obtaining a high-purity silica sol with a specified particle size according to an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions, advantages and significant progress of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings provided in the embodiments of the present invention, and it is obvious that all of the described embodiments are only some embodiments of the present invention, but not all embodiments;

all other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It should be noted that: